That's the one thing that I wouldn't want a woman doing to me sexually, quite frankly. I like a finger, or even more if she's into that down there, but a guys' ass is just way too nasty(although mine is shaved & relatively well-kept) to allow a girls' tongue down there. My ex-wifey did that to me one time & I just thought the whole time how nasty it must be for her(she asked me if she could though), so I couldn't enjoy it much.